{"id":3252,"date":"2012-12-05T09:50:00","date_gmt":"2012-12-05T07:50:00","guid":{"rendered":"https:\/\/www.bravomo.eu\/?p=3252"},"modified":"2020-01-20T22:09:07","modified_gmt":"2020-01-20T20:09:07","slug":"what-a-torque-power-graph-cant-say","status":"publish","type":"post","link":"https:\/\/www.bravomo.eu\/en\/what-a-torque-power-graph-cant-say\/","title":{"rendered":"What a Power\/Torque Dyno graph can\u2019t say"},"content":{"rendered":"\n
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Figure 1 – example of a dyno graph<\/p><\/div>\n

Often, what many bikers covet most at the end of tuning is a nice dyno graph (Figure 1) highlighting the differences between before and after tuning.<\/p>\n

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  1. Red\u00a0<\/span>Lines : Standard Motorcycles.<\/li>\n
  2. Blue\u00a0<\/span>Lines : Partial Stage I\u00a0with mufflers and tuning only.<\/li>\n
  3. Green\u00a0<\/span>Lines : Complete Stage I with air filter, mufflers, and tuning.<\/li>\n<\/ol>\n

    The difference is quite marked, both in terms of power and torque, yet merely reading the graph doesn’t truly indicate whether the tuning was carried out to perfection. Let’s try to explain.<\/p>\n

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    Figure 2 – VE Table<\/p><\/div>\n

    To obtain a dyno graph such as in Figure 1: keep the motorcycle in 4th or 5th gear at about 1600\/1800 rpm for a few seconds, and then accelerate, keeping the throttle fully open until you reach the maximum number of revolutions for the engine. To relate, in a partial but explanatory manner, the dyno graph to the map refer to Figure 2 which represents the table of Volumetric Efficiency (VE) of a cylinder. The highlighted column corresponds to a fully open throttle (Throttle Position = 100%).<\/p>\n

    The highlighted column is therefore the only part of the entire map table measured in a dyno graph.<\/strong><\/p>\n

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    Figure 3 – VE log<\/p><\/div>\n

    Figure 3 shows the same VE table, but this time the highlighted cells are those affected during the typical use of an engine. We see how these cells are many more than those in Figure 2 from a dyno graph.\u00a0It is therefore almost obvious to conclude that a typical dyno graph cannot tell if a motorcycle’s engine has been tuned throughout its complete range of use.<\/p>\n

    Now many of you are wondering how to tell if your bike’s tuning was or will be performed to perfection; no fear, there is an answer.<\/p>\n

    Science and Empiricism<\/h3>\n

    Tuning a motorcycle is a mix of science and empiricism. It’s like in the medical field – I hope doctors don’t take offense for comparing tuning a motorcycle to curing a patient. Judging the result follows the same method:<\/p>\n